


Thing

by CelestialSpace



Category: Voltron: Legendary Defender
Genre: Barebacking, Bottom Keith (Voltron), Finger Sucking, Hair-pulling, Hand & Finger Kink, M/M, Oral Sex, Post Season 7, Praise Kink, Shiro's new prosthetic, Trans Character, Trans Keith (Voltron), Trans Male Character, Trans Male Keith (Voltron), Vaginal Fingering, Vaginal Sex, authority kink, i guess, spitting in mouth mentioned, trans author
Language: English
Status: Completed
Published: 2018-08-13
Updated: 2018-08-13
Packaged: 2019-06-26 10:37:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,767
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15661521
Author URL: https://archiveofourown.org/users/CelestialSpace/pseuds/CelestialSpace
Summary: Shiro's new arm is detachable, need I say more?





	1. Chapter 1

**Author's Note:**

> The title of this is based off of Thing from the Adam's Family cause I thought it was really funny at 2AM last night when I was writing this. In this fic Keith is a FTM trans man so I will be using masculine terms for Keith's genitalia.
> 
> I'm technically considering this a crack fic cause I'm kinda embarrassed but I needed to write this. So the idea behind this fic is that Shiro's new arm floats, right? Well once it gets a certain distance away from him, he can still control it, but it doesn't float anymore. Therefore, it has to move around by other means.

Keith finishes drying his hair and collapses onto his bed. Meetings with people from the Garrison seem to drag on forever and they add the extra stress of everyone arguing. Each one feels like a Garrison Vs. Voltron match to see whose ideas will come out on top. Keith just wants to be able to relax for the rest of the evening without being bothered. Though, he probably wouldn’t mind if a certain starlight-haired man entertained him for a little while. Keith smiles at the thought and brushes his hair out of his face. Thinking of the man always makes him smile.

He’s startled from his thoughts by a knock at the door. “Who is it?” He’s not presentable to be seen by just anybody. Another knock rings through the door and he sighs, “It’s unlocked.” He hears it squeak open loudly and it shuts after, the lock clicking loudly in the silence of the room. Keith is quick to sit up but is confused when he sees nobody by the door. It isn’t until he hears a soft clacking on the metal floor that he looks down. A startled laugh escapes him and soon he’s doubled over and holding his stomach as he continues to laugh. Shiro’s new prosthetic is skittering across the floor like some kind of creepy insect. Keith’s sides ache and he’s breathless as he tries to stop laughing over the sight. The metal appendage crawls towards the bed on its fingertips. 

Keith takes a moment to gasp for air as his laughter finally subsides. He reaches down and lets the disembodied arm climb into his hand and hold on. “Shiro that was really funny, but you can come in now.” He calls out and lays the arm down in his lap. He waits for a moment but then it hits him that the he had heard the door lock. Wait, how did he even reach the doorknob anyways? Keith squints down at the prosthetic in his lap and as if Shiro can hear him from wherever he is, the hand touches his pointer finger and thumb to make an okay symbol. Shiro's hand then lays flat and begins tapping on his thigh. He watches it move for several moments before he realizes it’s tapping out in morse code. After it repeats one last time he realizes that Shiro is telling him that he’s in a meeting. Keith once more squints down at the hand and he swears that he can tell Shiro is smirking wherever he’s at. 

Shiro's hand uses its fingers to launch itself at Keith and it knocks him flat to his back. He pretends to swat at it, but he allows the hand to crawl up his chest. It gently drags fingers across Keith’s chin and he picks it up by the wrist to bring it closer to his face. He kisses the pad of a finger and it traces the seam of his mouth. It wriggles in his hands and he can’t help but smile at how ridiculous this feels. At the opportunity, Shiro's hand pushes a digit into the opening and presses into his wet mouth. Here he is, laying in bed and getting aroused by his boyfriend’s detached arm because it’s touching him, while its owner is who knows where in an important meeting. He sucks on the metal fingers like he would if Shiro was there with him; the prosthetic practically vibrates at the attention it’s getting. He pulls off the fingers with a loud pop and lets the hand rest on his chest again. 

With a tap against his sternum it moves down again; Keith isn’t quite sure what it’s doing, but a gasp is startled out of him when it pinches a nipple. He looks down to watch it slide to the other side of his chest to pinch the other. The panting Keith is hearing must be his own, he realizes, because he’s the only person in the room. Shiro’s hand deftly walks its way down Keith’s stomach and goosebumps ripple out across his skin. He grabs his shirt by the hem and pulls it over his head so that the hand can rest on heated skin. It stops to gently caress one of the scars beneath Keith’s pecs and suddenly Keith is breathless for a whole new reason. Balancing on its thumb and pinky, Shiro’s fingers trace across his stomach and pet at the hair beneath his navel as it moves further down. 

“Please,” Keith whimpers yet Shiro’s hand doesn’t move. “Please, Shiro,” A finger traces out a heart on Keith’s stomach and then it finally moves down to Keith’s waistband. After a slight struggle, Keith laughs and reaches down to help the hand remove his shorts. His shorts disappear off somewhere in the room like his shirt had. Shiro’s hand hesitates as it drifts across the skin between his hip bones. “I wasn’t wearing any.” A finger taps in, what could be, thought, but surprisingly Keith has a hard time reading emotions from a hand. Shiro’s hand finally starts to move to where Keith really needs him, where he’s wet and waiting for Shiro’s touch. Silver fingers trail across the coarse hair between Keith’s legs and falls to the bed between Keith’s thighs when he spreads them. 

The metal is almost warm when it presses against him; it rolls over Keith’s dick slowly and Keith writhes beneath that first touch. The hand dips down to gather some of the moisture that’s leaking out of his snatch and brings it back to Keith’s aching nub. The hand begins to almost vibrate again and Keith cries out at the extra stimulation. “Ah, Shiro-” The fingers press down harder against him, rolling over his cock at a desperate pace, “please!” With one last glide over him the hand moves down to Keith’s opening. Shiro’s fingers dip into the wetness gathering there and spreads it around and over his fingers. It pushes one finger in slowly, pulls out again, just to slip back in slightly further. The slow in and out helps relax him and he loosens up around the probing finger. 

Each of Shiro’s new fingers are massive, just one of his fingers is easily the size of two of his old ones, that though has Keith shivering, arousal shooting straight to his dick. Keith is already stretched around the one finger and the thickness of its joints drags beautifully along his inner walls. Keith claps a hand over his mouth to stifle his moans. Normally he has no problems when with Shiro, but Keith can’t be making loud noises when he’s technically alone in his room, even though Shiro’s new finger’s feel so good inside of and against him. The digit curls up and rubs against the bundle of nerves hidden inside of him; Keith is glad his mouth is already covered when he loudly moans. 

“W-wait, let me-” He calls out, he’s breathless and can’t even bring himself to finish his sentence as he rolls over. He brings the pillow down beneath his head and buries his face into the soft material. Hot air fans out across his face from where its buried in the pillow and he moans when he breathes and drags a lungful of Shiro’s scent in. He spreads his legs again in invitation to Shiro’s hand. He doesn’t feel the hand move back in close but he feels when it rubs down against his dick. The angle has the blanket rubbing against the front of his cock and the different textures pressing against him from either side at once has him trembling. He presses himself harder into the pillow to stifle his moans. Shiro’s fingers enter him again, filling him easily and without resistance. It fucks into him several times before he feels another finger tap against his hole. There’s enough wetness dripping out of him that the fingertip slides in easily but he doesn’t take it any further than that. It makes him sit there for at least a minute with one finger fully buried inside of him and the other only pressed in to the first knuckle. He rocks his hips experimentally and bites down on the pillow at the feeling. Shiro’s hand takes his movement as a good response and the second finger begins to slide in. It’s slower going this time, Shiro’s fingers are so thick that Keith feels completely full at only two fingers. Once they’re both fully seated inside they rock slightly in and out to rub gently over the cluster of nerves again. 

Shiro’s hand finally pulls almost all the way out before thrusting in again, “R-right there, Shiro, right there!” With each hard press in the fingers hit the same spot making Keith’s eyes roll back into his head and his body quake. He’s so wet that his arousal is dripping out of him and down onto his cock and even wetting the bed beneath him; the spring in Keith’s gut coils tighter and a whimper escapes his lips. Shiro’s hand can’t fuck him and touch his dick at the same time so instead it moves even faster and the slight vibration returns again. Keith grinds down against the bed and the dual sensations sends him higher and his legs tense as he makes the effort not to close them on Shiro’s hand. After a few more thrusts Keith finds himself cumming, a high pitched keen escaping to echo around the room as his body arches dramatically. Moisture gushes out of him and coats Shiro’s hand and the bed even more. 

Keith is boneless. He can’t move from the spread out position that he’s in, but he can’t bring himself to care. The wetness beneath him is uncomfortable but he’ll clean it up soon, maybe after a nap. He pants into the pillow until he’s able to turn his head to the side and breathe in cold air again. As he’s slowly winding down from his orgasm he feels Shiro’s hand pet his thigh before it lifts off the bed. Distantly Keith knows that Shiro must be close by if the hand can float again but he can’t find it in himself to think about it too much in his relaxed state. A flesh hand cards through his hair and pushes it out of the way so that his face is exposed. 

“There’s my boy.” Shiro settles between his still-spread thighs and leans down so that he’s hovering over his boyfriend. Shiro is a line of heat against his back and Keith groans. “You made quite a mess back here, baby.” His flesh hand rubs through the wetness between Keith’s thighs and pushes a digit into Keith’s gaping hole. He groans as he stuffs Keith with three fingers easily. “So wet and open for me.” Keith arches slightly into the touch, his body already trembling from the overstimulation. “So ready for me-” Keith eyes snap open as he hears Shiro’s belt being undone. He can already feel himself getting wet again.


	2. Chapter 2

**Summary for the Chapter:**

> What followed

**Notes for the Chapter:**

> All the positive responses inspired me to write a follow up chapter of what happened after Shiro came back to the room! This ended up being different than I intended but I'm pretty happy with the direction it went. I hope you like the new chapter!! This is the quickest I've ever written and posted a chapter but you guys really made me excited to make this and post it!

The belt clatters to the floor and Keith turns his body slightly so that he can see over his shoulder. From his position flat on the bed Shiro seems to tower over him. His eyes are molten silver as his hot gaze rakes across Keith’s prone body. “God, look at you, baby.” Shiro leans back over him again and places a gentle kiss on his shoulder blade. “Did you enjoy yourself?” With a whimper Keith barely nods as he’s still feeling the hazy afterglow from his last orgasm. Shiro’s hands start at the back of Keith’s knees and slide up the back of his thighs till they reach his ass; Shiro grabs a handful of Keith’s pert bottom and kneads them softly. With a squeeze he spreads Keith’s cheeks to expose Keith’s most intimate place. Shiro groans at the sight of Keith’s fucked open hole and the sound goes straight to Keith’s dick. The older man ducks down and swipes his tongue over Keith’s opening once, licking up the juices coating it, and he groans deep in his chest. “Oh baby, I’m going to ruin you.” Keith’s breathing picks up and he clutches the pillow tightly in his hands.

With Keith’s head turned away from the pillow his cheek is pushed up making the heavy blush and dilated pupils more obvious to Shiro. With a galaxy swimming in the depths of his eyes, Shiro’s never seen a boy more beautiful than the one beneath him. With a quick, chaste kiss to Keith’s face Shiro straightens back up and reaches to pop the button on his collar. “Wait!” Keith crying out immediately makes Shiro freeze. Had he done something wrong? “Leave it on,” Keith’s blush darkens in color, “Leave all of it on. I- I like-” Keith bites his lip and Shiro takes pity on him. 

“You like how my clothes feel against your skin when you’re sensitive like this?” Keith nods and shifts around in embarrassment. At the admission Shiro lays down against Keith, pressing fully against him from cheek to foot. With the weight of his body, Shiro’s bulge is digging into Keith’s plush ass and it takes little hip movement to get it pressed between those round cheeks. Keith’s breath shutters out of him and when Shiro grinds his hips down into the smaller man; the hard line of Shiro’s dick presses roughly against Keith’s hole through the material of his uniform. “Do you want me to fuck you while I’m fully clothed, baby?” Shiro’s voice is breathy when he asks but he already knows the answer. 

“Yes, Capitan.” Shiro wasn’t expecting the title but the sound of Keith whispering it makes Shiro’s dick throb. The urge to be soft with Keith leaves him entirely. Shiro roughly bites the curve of Keith’s shoulder and his boyfriend cries out. He grinds harder against Keith’s ass and the man writhes beneath him. Sitting back up, Shiro pops the button on hem of his uniform top open and parts the material to either side of his waist. The button of his pants are next to go and he only pulls the material down far enough to get his dick out. His cock is painfully hard and dripping. Nothing turns him on quicker that his boyfriend being soft and pliant beneath him. Just thinking about his hand fucking Keith open in another room had him half hard throughout the entire meeting. 

Shiro’s prosthetic holds Keith open while his flesh hand strokes at his own cock. The sight of Keith’s sopping wet and fucked open hole has his dick weeping in anticipation. “I thought you were going to ruin me, Capitan?” Shiro’s eyes snap to Keith’s at the taunt. He raises an eyebrow at the younger man who bats his eyelashes sweetly with an innocent expression. Needing only a slight movement, Shiro’s hand slips from holding him open to plunging its thumb deep inside of him. Keith’s back snaps into an arch and his loud moan echos around the room. 

“What was that, baby?” Panting, Keith is unable to talk and shakes his head. “Mm, that’s what I thought.” Keith buries his face back into the pillow as he’s once again being fingered by Shiro’s new arm. Keith can barely keep quiet with the new feeling; Shiro’s thumb feels completely different from the other fingers, the large middle knuckle drags against his walls in a new way, yet it doesn’t touch anywhere that Keith is desperate for him. Shiro changes the angle and Keith mewls, a deep moan from Shiro following his sound. “That’s it baby, you take me so good.” He switches his thumb out for his forefinger and middle finger again, he roughly fingers him open, hitting him deep where he likes it every time. “I want you to come again before I’m inside of you. I want to watch you. Then you’re going to cum on my cock like a good boy.” More fluids leak out of Keith as Shiro talks and his fingers squelch through the mess. Shiro has to grasp the base of his dick tightly because it’s too early for him to cum and he’s just getting started with Keith. 

As metal fingers continue to push in and out of Keith’s slick hole, Shiro reaches out with his flesh hand to press against Keith’s dick. The slickness from his own precum makes it easy to rub over the soft nub with quick strokes. Unable to hold back his moans at the dual sensations, Keith is openly crying out into the room. It doesn’t take long before Keith literally comes apart in his hands. Keith’s body quakes through his second orgasm and when he finally falls limp again his body continues to shiver with aftershocks. He’s entranced by the extra fluid leaking around his fingers out of Keith’s spent hole. Shiro slides his fingers free and licks the wetness from the digits with a moan. Shiro leans down to nip Keith’s earlobe and the younger man shivers with a little, “Ah-” Shirio presses close enough so that the rough material of his uniform brushes Keith’s sensitive skin but not close enough for them to actually touch each other. He presses a kiss to Keith’s ear. 

“I’m going to ruin you.” Shiro sits up and his new prosthetic moves to grab ahold of Keith. The hand is so massive that with it’s fingers extended Shiro can wrap around either side of Keith’s narrow hips. With just the one hand he’s able to lift Keith’s hips and hold them up so that he can slide inside easily. Keith’s walls are warm and wet as Shiro slips in to the hilt. When Keith whimpers, Shiro pulls back almost all the way, just his head left nestled in that warmth. He waits there for a moment to tease them both but he can’t make himself wait for long. With just the floating hand he’s able to pull Keith’s body off and back onto his dick to meet the snapping of his hips. 

With each thrust in, air is pushed out of Keith with a little high pitched, “Ah!” Shiro leans just enough so that he can curl his fingers in the hair at the base of Keith’s neck; with a hard tug Shiro pulls Keith’s head back and his other hand maneuvers Keith’s hips so that his back is arched in a beautiful bend. Shiro groans at the sight of his boyfriend’s delicious ass which is now stuck up into the air. This new angle allows Shiro to drive even deeper into his boy and his body begins shaking harder with every thrust into him. “P-please, Sh-Captain, gonna cum again, let me cum again!” He wails as his walls are fluttering around Shiro’s shaft and it makes him only increase his speed. 

“I told you I wanted you to cum on my cock, so be a good boy and cum.” A full body shiver works its way through Keith and he scrabbles for something to hold on to. With another thrust Keith starts cumming, the wetness drips down his thighs and makes Shiro’s cock even wetter. His orgasm is silent but his mouth is dropped open wide as if he’s screaming. If he had the angle, Shiro would take the opportunity to spit in his boyfriend’s mouth, make him even wetter as their fluids mix. That dirty thought has him driving into Keith even harder and Shiro lifts him up into a kneeling position by his hair. A squeak escapes him as he’s pulled up till his back is flush with Shiro’s chest. The button and pin attached to the chest of Shiro’s uniform scrapes against Keith’s sensitive skin and he whimpers. 

His third orgasm has him weak and spent. Every drag of Shiro’s cock deep inside of him sends sparks throughout his body and Keith can barely breathe through the overwhelming feeling. “Captain, please! I need to feel your cum!” Keith begging him does something to Shiro, he groans and feels himself draw closer to his release. He pushes Keith back down onto his stomach and plants his hand between Keith’s shoulder blades. He pounds into him at a brutal speed, his boy below him crying out at the sensation. Keith is so overwhelmed by the insistent pounding of his thoroughly-used hole that tears well up and spill over his cheeks and he can’t stop himself from crying out. Shiro sinks in one last time before he pulls out completely; Shiro’s silver hand holds Keith open once again as his flesh hand wraps around his cock and begins to stroke it frantically. 

Keith looks over his shoulder as he continues to cry in his overwhelmed state. He watches Shiro desperately chase his own release as he looks down at his quivering boyfriend’s body. “Shiro, please, cum on me! I need to feel it!” He can hear the desperation in his own voice and Shiro groans deep in his chest, he throws his head back and his eyes finally close. Metal fingertips dig deep into his skin as shiro’s hand holds onto him for dear life. With several more rapid strokes and a loud moan, Shiro finally cums. Spurts of white splatter over Keith’s ass, exposed holes, and his back. Shiro jerks himself through his orgasm and Keith bites his lip at the sight. The silver hand leaves Keith to push Shiro’s forelock back and hold it out of his face as he pants heavily. Shiro relaxes back to settle onto his heels as he basks in the afterglow of his orgasm. When his eyes finally flutter open he finds Keith is already looking at him. 

Shiro fights the urge to want to collapse onto the bed and instead dips forward to kiss Keith’s shoulder, ear, cheek, and then finally he plants a sweet kiss on Keith’s lips. Keith hums into the kiss but it morphs into a moan when Shiro’s hands press into the back of his thighs. Shiro runs his hands over his skin and then through the mess he made on Keith’s ass and back. Using his hands he rubs his cum into Keith’s skin and the Galran side of him wants to purr over Shiro marking him so that anyone who can sense it will know who he belongs to. This had become a regular occurrence for them but it still makes Keith weak every time. 

“You’re mine,” Shiro starts peppering Keith’s sweaty face with kisses, “and I love you.” Keith blushes at the words but they warm him to the core. 

“I love you too.”

**Notes for the Chapter:**

> Clearly comments inspire me to write faster, so thanks to everyone who commented on the last chapter! I hope this chapter was what you were hoping for!! Feel free to stop by my [Tumblr](https://www.tumblr.com/blog/cosmosmoose) and leave me a fic request if you want, and I'll write you something!!

**Author's Note:**

> Thanks for reading! I might be willing to write a part 2 of what comes next if anyone is interested?? I'm so bad at tagging, so let me know if there's anything I need to add.  
> Please, feel free to leave a comment or some kudos if you want or you can come feel free to hit me up on [Twitter](https://twitter.com/AstronautMoose)


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